William Christie and the period-instrument ensemble Les Arts Florissants return to Lincoln Center Oct. 29 and 30 with a little-known religious opera.

By the standards accorded to most operatic protagonists, the eponymous saint of Roman Baroque composer Stefano Landi's 1632 dramma musicale, Il Sant'Alessio, is an unlikely hero. Based on the life of the fifth-century mendicant, Alexius, Landi's saint spends the last days of his earthly existence welcoming death while disguised as a peasant camped out under a stairway in his own father's house; he allows himself to be abused by the hired help and imagined dead by his anguished family. Like Melville's scrivener, Alessio is a soul utterly etched by pathos and self-imposed privations — a character who would "prefer not to" when confronted with the simple comforts of life. All this might seem like an inert plot for an opera considered a masterpiece of the early Baroque, were it not for the fact that Landi made certain that his saint could sing.

The opera, says William Christie — who this month brings his superlative period-instrument orchestra, Les Arts Florissants, and a first-rate cast of voices to Lincoln Center's Great Performers series for two semi-staged concert performances of the rarity in the Rose Theater — is remarkable for the depth with which it plumbs the psychology of its main character, sung here by acclaimed French countertenor Philippe Jaroussky. "Nothing really happens, essentially. There is no great violence as there is in other Baroque works," says Christie. "Instead, we are talking about the spiritual life of someone who's chosen a rather unusual path to follow — to renounce life, to become holy."

Commissioned by brothers Taddeo and Cardinal Francesco Barberini — nephews of Pope Urban VIII — in honor of the 1631 Roman carnival season, Il Sant'Alessio stands as a thrilling synthesis of Baroque sonorities and styles. Landi, a contralto in the Sistine Chapel's papal choir, evokes the choral writing and counterpoint of Palestrina, the word-painting of a Monteverdian madrigal or arietta, and overture-like canzonas. "I don't think you can talk about a single, defining aesthetic in the 1620s and '30s. Everything was up for grabs. And this is obviously one of those pieces in which you sense something new is happening," says Christie. "It's got the marvelous sort of rhythmic drive, and a very similar wonderful melodic simplicity to Monteverdi. It has the same kind of timbre and color you get from a small string orchestra with a very large continuo. The salient point, the big difference, is that we're talking about, essentially, a Roman choral-opera. The choir is omnipresent. It organizes and sort of defines the space as well." For the Rose Theater performances, the choral duties will be assumed by la Maîtrise de Caen, an acclaimed boys choir hailing from the Lower-Normandy capital.

If the work were esteemed for its music alone, Sant'Alessio might warrant a footnote in the annals of opera and the occasional performance excerpt. But the work's libretto by Giulio Rospigliosi — who later become Pope Clement IX — is a similarly masterful hodgepodge of tragedy, commedia dell'arte, Counter-Reformation fervor, and supernatural spectacle that imparts genuine dramatic impetus to Alessio's ascension; the text also happens to be the first based on the life of a real person. "The libretto has everything," says Christie. "Rospigliosi understood that you can mix tragedy and comedy, light and heavy, tragic and less tragic — or even frivolous — and things work. It's that same mix essentially that one gets in a good Shakespeare play."

Director Benjamin Lazar, whom Christie contacted following Lazar's acclaimed production of Molière and Lully's comédie-ballet, Le Bourgeois Gentilhomme, in France several seasons ago, agrees. "What is often difficult in opera is not little action, but a bad text. I like operas where the libretto is created by a real writer, and Rospigliosi is one of the best Italian librettists of this period," observes Lazar. "He perfectly employs the principle of Horace — docere et delectare, to teach and to entertain."

Lazar, a specialist in Baroque gesture and rhetoric, directs fully staged productions of Sant'Alessio in Caen, Paris, Nancy, and Luxembourg, but says that he intends to conserve the opera's distinct dramatic energy in the semi-staged New York performances. "Work on gesture helps me animate the long dialogues between the characters," he says. "If a singer plays only the feelings, without working on the rhetorical aspects of the text, he can't find the real energy of the recitar cantando — which was directly inspired by the art of rhetoric of ancient Rome — and it becomes boring. It would be like playing Landi with piano and modern violin — you wouldn't be able to find the appropriate energy."

While both Christie and Lazar are essentially purists of their respective fields, they plan to present Landi's opera in a way that is at once historically informed and forward-looking — employing the types of educated approximations that have come to define the ongoing period-instrument and Baroque opera revivals. While Les Arts Florissants' superb 1996 Erato recording of Il Sant'Alessio utilized a mix of male and female voices — with Alessio being sung by French soprano Patricia Petibon — here Christie and Lazar have recruited a cast consisting almost entirely of countertenors, the modern equivalents of the voices heard during the era of castrati in which Landi lived. Perhaps most notably, the casting includes countertenors Xavier Sabata, Max Emanuel Cencic, and Jean-Paul Bonnevalle in the archetypal female roles of Mother, Wife and Nurse, respectively (boys and castrati would have been cast in the roles during the Church's prohibition against women on stage).

The curious authenticity of male treble voices in female roles is a dramatic and musical revival effort that Christie feels audiences are ready for. "When I was recording the opera, I just didn't have this extraordinary luxury of having these kinds of male soprani and male alti as I do today," remarks Christie. "So I thought, given the fact that we've got some extraordinary male falsetto voices on the market right now, why don't we try an all-male cast as was done back in those days?"

For Lazar, the casting of men in female roles highlights the inherent dramatic challenges of presenting any theatrical work, regardless of its origin or ideology. "In Japan, India, or China, the female roles are played by men in traditional theater, and nobody in the audience laughs, except when the actor wants to make them laugh — I assure you that Japanese people do cry when the geisha is dying, and everybody believes the situation. A French spectator who witnessed the first production of Il Sant'Alessio in 1632 wrote that the audience was totally excited, sighing, crying, especially when the castrati and boys were singing. That is the power of theater."

Christie concurs, noting that, despite the otherworldly elements, the opera's draw is universal. "It's a story that has great feeling," he says. It deals with human suffering and human tragedy and human emotions. As in all good operas ... it's all about human drama."